CVuEye.vin - Access violation when accessing pixel data

Programming Questions C-style API
1

I use the CVuEye.vin driver in a 64 bit VS2017 C++ project to access a IDS uEye camera.
I can initialize the camera without problems but get a read access violation if i grab an image with the following code:

void* pixPtr = nullptr;
intptr_t XInc, YInc;
cvbResult = Snap(pImage->Handle());
cvbResult = GetLinearAccess(pImage->Handle(), 0, &pixPtr, &XInc, &YInc);
int c = *((unsigned char*)pixPtr);// !! read access violation

The GetLinearAccess function returns a pointer != null and correct XInc/YInc values.
But if i try to read from the pixeldata pointer I get a ‘read access violation’.

Any idea?

2

Hi POI,

Maybe your image is invalid or locked/opened in another process? Can you check IsImage(pImage->Handle())?

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3 Likes
3

Hi POI,

everything @usernv said is correct.

Your issue would suggest that the image gets deleted (or moved or …) between line 4 and 5.
Could this be a lifetime issue of pImage?
Is your code snippet an approximation of your code (i.e. there is stuff happening between line 4 and 5) or the full code?

4

Hi usernv and c.hartmann

Thanks for your reply.
The code snippset is exactly the code I use in my application.
Initially I used the C++ API reading from stream with GetTimedSnapshot() or WaitFor().
The Methods deliver a valid image, but any access to the pixel data leads to the access violation.
I use the code in a Camera class that loads/initializes the camera device in the constructor and reads the images via a Read() method. The Read() method is called from a separate grabbing thread.
Using the CVMock.vin driver the code works perfectly.
May be a problem with the used ‘CVuEye.vin’ driver?
Next week I have the chance to test the code with the ‘GenICam.vin’ driver…

5

@POI, I sent you a new driver version which should fix the problem. I would highly suggest to use cameras which comply with the GenICam standard though and thus use the GenICam.vin whenever possible. The CVuEye.vin is deprecated and will not further be maintained.

6

Yeah, the new ‘CVuEye.vin’ fixes the problem.

Thank you very much.